Biomedical subjects

R Putz

Publications and source records attributed to R Putz.

At least 55 records · Page 3Linked to original sources

PubMed1999

Liposuction technique and lymphatic lesions in lower legs: anatomic study to reduce risks.

Liposuction is a standard procedure in plastic surgery. Especially, lipectomy with suction of the lower extremities has been of greater interest in recent years. Until now, however, there was no definite information about the integrity of epifascial lymph collectors during this procedure. To study the effect of liposuction devices on lymph vessel injury, postmortem lymphatic preparations were done in five human cadavers (10 lower extremities). Conventional liposuction with a blunt 4-mm cannula and a dry technique was used. Adiposuction was performed either in parallel to the extremity axis and, therefore, in parallel to the superfascial lymph vessels or transversally in an 80- to 90-degree angle to the extremity. Careful surgical preparation of the regions followed. A specific macroscopic lymph vessel injury score was applied to differentiate 3 degrees of lymph vessel lesions according to the extravasation of patent blue. In all lower extremities, postmortem lymph flow occurred as indicated by patent blue staining of the lymph vessels. Lymph vessel injury was more severe in areas where liposuction was performed transversally, vertical to the extremity's axis, than in those after a longitudinal procedure. The difference was statistically significant (p < 0.01). The volumes of adipoaspirate and of the compared regions were comparable between both groups, verified by circumference measurements. Longitudinal liposuction of the lower extremities is unlikely to cause major lesions of epifascial lymph vessels and, therefore, should be preferred in comparison to liposuction vertical to the extremity.

Aged↗

PubMed1998

Changes in cadaveric cancellous vertebral bone strength in relation to time. A biomechanical investigation.

STUDY DESIGN: A biomechanical study was conducted during a 3.5-day period to test for changes occurring in pullout strengths of cancellous screws inserted into human cadaveric vertebral bodies. OBJECTIVES: To quantify, within the testing time of 3.5 days, the possible changes to the mechanical properties of cadaveric vertebral bodies, resulting from structural degradation caused by postmortem, time-dependent, autolytic processes during mechanical testing of implant-bone biomechanics. SUMMARY OF BACKGROUND DATA: Biomechanical testing of whole spinal implants and analysis of the screw-bone interface of spinal implants is an area of clinical interest that frequently requires the use of cadaveric spine specimens. Changes in vertebral bone properties during the testing period may invalidate experimental results, but no data are available on degradation of bone during the testing period. METHODS: Anterior oblique cancellous screws were inserted into human vertebral bodies from which the ventral cortex had been removed. The pullout strength was measured at 0, 24, 60, and 84 hours after insertion. The tests were performed on 48 human vertebral bodies, which were stored by freezing to -23 C, thawed for testing, and kept at room temperature during the testing time for as long as 84 hours. RESULTS: The axial pullout strength showed no statistically significant change during 84 hours (P = 0.15). There were no significant differences attributable to vertebral level from T4 to L4, probably because the ventral cortices had been removed (P = 0.7). CONCLUSIONS: During 3.5 days, there were no changes in pullout strength of vertebral cancellous bone. In biomechanical studies during a maximum period of 3 days with a small number of cadaveric spines (e.g., four spine specimen) the time-dependent changes in pullout strength play a less significant role than do the interspine differences. Interspine differences should be regarded as an important factor to be considered in the design of biomechanical tests.

Autolysis↗

PubMed1998

Fibrocartilages in the extensor tendons of the interphalangeal joints of human toes.

The extensor tendons of the fingers and toes form part of the capsule of the interphalangeal joint and press against the proximal phalanx during flexion. Previous work on the fingers has shown that there is a "sesamoid" fibrocartilage on the deep surface of each tendon that labels immunohistochemically for a variety of glycosaminoglycans and collagens. However, we know little about the molecular composition of the tendon in the toes. This question is of special interest, because the mechanics of the interphalangeal joints differ in the upper and lower limbs-the toes balance the forefoot, distribute load during the gait cycle, and transmit the pull of larger muscles. This means that their extensor tendons are more often under higher tension than those in the fingers. Here, we report the presence of an equivalent fibrocartilage and compare its immunolabelling characteristics in all the toes. Six forefeet were removed from elderly cadavers, and the interphalangeal (IP) joints were fixed in 90% methanol. The extensor tendon and its enthesis were dissected out from the IP joint of the big toe and from the proximal interphalangeal (PIP) joint of all lesser toes, decalcified, cryosectioned, and immunolabelled with a panel of monoclonal and polyclonal antibodies for type I, II, III, and VI collagens; chondroitin 4 and 6 sulphates; and dermatan and keratan sulphate. Antibody binding was detected with the Vectastain ABC Elite avidin-biotin-peroxidase kit (Vector Laboratories, Burlingame, CA). The extensor tendon in all the toes had a metachromatic, sesamoid fibrocartilage on its deep surface that immunolabelled for all glycosaminoglycans and for type I, III, and VI collagens. Labelling for type II collagen was seen in the sesamoid fibrocartilage of all toes but was particularly characteristic of the 2nd through 5th toes. The immunolabelling patterns of the enthesis fibrocartilage were similar in all toes and to results reported previously for fingers. The normal occurrence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes is in contrast to our published data on the fingers. The finding can be related to the more constant loading of the tendon in the toes. The greater prominence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes could be related to a difference in joint position during walking between the 1st toe and the 2nd through 5th toes--the PIP joints of the latter are usually more flexed than the IP joint of the former.

Adult↗

PubMed1998

An MR-based technique for quantifying the deformation of articular cartilage during mechanical loading in an intact cadaver joint.

The objective of this study was to develop an MR-based technique for quantifying the deformation of articular cartilage during mechanical loading in an intact cadaver joint at high spatial and temporal resolution. A nonmetallic pressure device was constructed for applying loads of >1000 N to a femoro-patellar articulation within an extremity coil of a clinical 1.5 T MRI scanner. Digital image processing methods were used to determine the location- and time-dependent cartilage deformation in consecutive 2D fat-suppressed FLASH images. Additionally, three-dimensional reconstruction of the cartilage was performed from 3D fat-suppressed FLASH image data. During the first 10 min of static compression, thickness changes between 10 and 30% were observed. Thickness changes greater than 50% and volume changes of 20% were recorded after 3 h. The technique permits analysis of the load and time-dependent mechanical behavior of articular cartilage in its natural environment.

Adult↗

PubMed1998

[Anatomy of the labro-capsular complex].

The acetabular labrum appears as a bundle of distinctly circular lined up collagenous fibers. It surrounds the limbus tangentially and is separated from the cartilagenous covered facies lunata through a thin gap (fissure) except of a small zone in the craniocaudal part. The labrum is strongly fixed with the transverse acetabular ligament. A vascular anastomotic ring surrounds the capsular attachment. It derives its blood supply especially from the superior gluteal vessels, the obturator artery and one ascending branch of the medial femoral circumflex artery. The innervation of the acetabular labrum is coming from a branch of the nerve to the quadratus femoris muscle and from the obturator nerve. There are all types of mechanoreceptors in the labrum. The acetabular labrum is able to exert a high tensional force on the rim of the acetabulum. This plays a very important role in view of the physiological, load depending incongruity of the articulating parts of the hip-joint.

Acetabulum↗

PubMed1998

Correlation of femoral and lumbar DXA and calcaneal ultrasound, measured in situ with intact soft tissues, with the in vitro failure loads of the proximal femur.

The objective of this study was to determine experimentally the sex-specific correlation of femoral and lumbar DXA and calcaneal ultrasound, measured in situ, with the in vitro failure loads of the proximal femur. Fifty-eight cadavers with intact skin and soft tissues (34 male, aged 81.2 +/- 8.7 years; 24 female, aged 83.7 +/- 10.6 years) were examined. The bone mass of the proximal femur and the lumbar spine were determined using dual-energy X-ray absorptiometry and the ultrasonic properties of the calcaneus with quantitative ultrasound. Afterwards, the right femora were excised 18 cm distal to the minor trochanter, and their load to failure determined with a material testing machine. Femoral fracture loads were significantly higher in males than in females, both before and after correcting for body height and weight. Femoral neck bone mineral density (BMD) was significantly correlated with femoral failure loads (r = 0.65 all specimens, 0.57 males (0.64 after excluding trochanteric fractures) and 0.77 females; p < 0.001). The correlations with the ultrasonic Stiffness Index of the calcaneus were in a similar range (r = 0.67 all specimens, 0.48 males (0.64 after excluding trochanteric fractures) and 0.65 females; p < 0.001). The correlations between femoral failure loads and the spinal BMD were lower (r = 0.40, p < 0.01), particularly in males (r = 0.30, not significant). In contrast to previous experimental investigations on excised bones, our results are consistent with clinical studies that have reported that ultrasound and femoral DXA have a similar ability to predict the risk of hip fracture.

Absorptiometry, Photon↗

PubMed1998

Quantitative relationships of normal cartilage volumes of the human knee joint--assessment by magnetic resonance imaging.

The objective of this study was to assess the normal range of cartilage volumes in the knee joints of healthy adults, the ratio between the patellar, femoral, and tibial cartilages, and the correlation of the volumes with age, body weight, height, body mass index (obesity), patellar bone size, and the diameter of the tibial head. We examined the knee joints of nine healthy volunteers and eleven normal post-mortem specimens with an age range of 24 to 82 years. The cartilage volumes of the patella, femur, medial tibia and the lateral tibia were quantified, using a fat-suppressed FLASH-3D sequence (resolution 2x0.31x0.31 mm3) and digital postprocessing, involving three-dimensional reconstruction. The mean total volume of the knee joint cartilage was 23,245 mm3, the relative standard deviation (CV%) 19%, and the range 16,341 to 33,988 mm3. In the patella, femur and tibia, the CV% amounted to between 22 and 25%. These joint surfaces occupied a relatively variable proportion of the total knee joint volume, the percentage of the patella being 11 to 22%, that of the femur 54 to 69%, that of the medial tibia 7 to 12%, and that of lateral tibia 11 to 16%. The volumes of the lateral tibia were systematically higher than those of the medial tibia (P<0.001). There was no significant correlation of the knee joint cartilage volume with age (r=+0.05), body weight (r=+0.38), height (r=+0.39) or body mass index (r=+0.29), but a relatively high correlation with the diameter of the tibial head (r=+0.78, P<0.001). After normalising the volumes to this diameter, the CV% of the total knee joint cartilage volume was reduced to 13%, its variation being 12 to 21% in the patella, femur and tibia. MRI is available for measuring cartilage volume during growth, functional adaptation, and tissue loss in degenerative joint disease. The study shows that a wide variation of cartilage volumes exists in the knee joints of normal adults. To reduce the variability between individuals, the cartilage volumes may be normalised to the head of the tibial diameter.

Adult↗

PubMed1998

The distribution of cartilage thickness in the knee-joints of old-aged individuals -- measurement by A-mode ultrasound.

OBJECTIVE: To provide data on the normal distribution of cartilage thickness in the knee joints of old-aged individuals. DESIGN: The accuracy and reproducibility of cartilage thickness measurements were evaluated with A-mode ultrasound, and the cartilage thickness distribution was examined throughout both knee joints of nine individuals aged between 62 and 94 yr. BACKGROUND: Data on the variation of cartilage thickness in the joint surfaces are relevant for the design of computer models of diathrodial joints and for surgical and arthroscopic procedures, particularly the calculation of cartilage material properties from indentation tests. METHODS: A 12.5 MHz A-mode ultrasound transducer was used, and after determining the accuracy and reproducibility of the system in comparison with CT arthrography and anatomical sections, the cartilage thickness was measured throughout the knee at 256 coordinate points. RESULTS: A-mode ultrasound yields results consistent with established methods. The cartilage thickness is distributed regularly in the knee-joint of older individuals. However, the absolute values are considerably lower than those previously reported for younger people, the mean (and maximal) thickness being 2.0 mm (3.3 mm) in the patella, 1.9 mm (3.3 mm) in the femur, and 1.9 mm (3.5 mm) in the tibia. CONCLUSION: If the results of computer models or surgical strategies are to be applied to the demographically important group of older individuals, the typical distribution of articular cartilage thickness in this group should be taken into consideration.

Journal Article↗

PubMed1998

Prediction of vertebral failure loads from spinal and femoral dual-energy X-ray absorptiometry, and calcaneal ultrasound: an in situ analysis with intact soft tissues.

The objective of the current study was to determine the correlation of spinal and femoral dual-energy X-ray absorptiometry (DXA) and calcaneal ultrasound, measured in situ with intact soft tissues, with the in vitro failure loads of lumbar vertebral bodies. Forty-nine cadavers with intact skin and soft tissues (32 men aged 82.1 +/- 9.0 years, 17 women aged 83.1 +/- 10.1 years) were examined. The bone mineral content (BMC), the projectional area, and the bone mineral density (BMD) of the lumbar spine and proximal femur were determined with DXA, and the ultrasonic properties of the calcaneus with quantitative calcaneal ultrasound. The fourth lumbar vertebra was then excised with adjacent intervertebral disks and its mechanical failure load determined, using a materials testing machine. Absolute fracture loads were significantly higher in men than in women, but they were similar after adjusting for body weight and height. Spinal DXA was significantly associated with vertebral failure load (r = 0.62 combined; r = 0.54 men; r = 0.58 women). Femoral DXA (r = 0.46) and calcaneal ultrasound (r = 0.48) showed somewhat lower correlation coefficients, with the speed of sound (SOS) being able to add predictive information in a stepwise regression model. Normalizing the vertebral failure loads to body weight and height reduced the correlations, with only spinal DXA yielding a significant relationship. Our data suggest that previous in vitro studies may have overestimated the association between spinal DXA and vertebral failure loads, presumably because measurements were performed on excised bones, but not in situ in the presence of soft tissue inhomogeneity. The results indicate that, even in a population of old age and under in situ conditions, spinal DXA may still be somewhat better than femoral DXA and calcaneal ultrasound in predicting vertebral failure loads.

Absorptiometry, Photon↗

PubMed1998

Thickness of the subchondral mineralised tissue zone (SMZ) in normal male and female and pathological human patellae.

The objective of this paper was to analyse sex differences of the thickness of the subchondral mineralised tissue zone (SMZ), and to find out whether systematic changes of SMZ thickness are associated with naturally occurring, non-full-thickness cartilage lesions of human patellae. In 32 methyl-methacrylate-embedded specimens (16 normal, 8 with focal medial, and 8 with lateral lesions) the SMZ thickness was determined, using a binocular macroscope and an image analysing system. In each case, the thickness distribution was reconstructed throughout the entire joint surface. The maximal and mean SMZ thicknesses were significantly higher in males than in females (P < 0.01). In normal patellae and those with lateral lesions, the thickness was significantly thicker laterally than medially (P < 0.05), but it was not in specimens with medial damage. Patellae with medial damage exhibited a significantly lower total mean and lateral mean (P < 0.05). A lower SMZ thickness was found directly beneath medial lesions than beneath lateral ones, but the local thickness was always in the range of that observed in normal specimens. We conclude that differences of patellar SMZ thickness exist between males and females. Naturally occurring cartilage lesions appear, however, not to be associated with local changes of SMZ thickness, but they may be associated with an altered regional distribution pattern within the joint surface.

Aged↗

PubMed1998

The distribution of cartilage thickness within the joints of the lower limb of elderly individuals.

The objective of this study was to investigate the normal distribution of cartilage thickness in the major joints of the lower limb in elderly individuals. A 12.5 MHz ultrasound transducer was used to measure the cartilage thickness in the right and left hip, knee and ankle joint of 10 individuals aged between 62 and 99 y. Distribution patterns of cartilage thickness were derived by b-spline interpolation and the average distribution computed in each surface. The maximum cartilage thickness in the hip joint was 2.6 (+/-0.36) mm and the mean thickness 1.3 (+/-0.17) mm. The CV% (a measure of thickness inhomogeneity within the joint surface) was 32%. In the knee, the maximal and mean values were 3.8 (+/-0.46) mm and 1.9 mm (+/-0.24) mm, respectively (CV% = 34%), and in the ankle 1.7 (+/-0.25) mm and 1.0 (+/-0.16) mm (CV% = 32%). Systematic differences existed between both sides in the knee, the distal femur showing a significantly greater thickness on the right. While the mean and maximal thicknesses were systematically higher in the knee than in the hip, and in the hip higher than in the ankle (P < 0.05), there were no systematic differences in the thickness inhomogeneity of the 3 joints. Only the malleolus showed a somewhat more uniform thickness than the other joint surfaces. The variability between individuals was similar for all joints for mean thickness, but the interindividual variability of the maximal thickness values was highest in the knee and lowest in the ankle. Whereas the cartilage thickness distributions in the joints of the lower limb have been suggested to reflect the pressure distribution within the articular surface, the absolute thickness is proposed to be a function of dynamic loading (range of motion) during gait, rather than being a reflection of the static articular pressure.

Adaptation, Physiological↗

PubMed1998

Variations of the frontal exit of the supraorbital nerve: an anatomic study.

Until now, it has been taken for granted that the point of emergence of the supraorbital nerve is by way of a notch or a foramen at the border of the inner to the medial third of the supraorbital rim. In contrast to several anatomic textbooks, we noticed that the exit point was repeatedly not at the site where anticipated when implanting lid springs for facial palsy. This gave us the idea of investigating these variations and how big they are, because most open and recent endoscopic forehead lift techniques have relied on a constant exit point of the supraorbital nerve. A total of 507 macerated skulls (1014 orbits) from three anatomic collections in Austria and Germany were studied. All skulls were adult European skulls gathered from the prehistoric age up to the twentieth century. Additionally, 18 fixed cadavers (36 orbits) and 25 fresh cadavers (50 orbits) were studied. These data were not included in the statistical analysis but in the discussion. The anatomic measurements on the skulls were carried out with an anthropometric calliper. The examinations concentrated on the configuration (notch/foramen) and the number of exit point(s) on the supraorbital rim, the vertical distance from the supraorbital rim, and the distance from the nasion to the various exit point(s). Combining all of these parameters, 74 percent of the skulls showed asymmetric findings between the right and left orbits. In 15 percent of both orbits, the supraorbital nerve left the orbital cavity already in its two branches, the medial and lateral branch, either through a notch or a foramen, the foramen being sometimes the exit of a supraorbital canal. The average distance from the nasion to the frontal notch/foramen was 25 mm on both orbits (range 16 to 55 mm) and to the supraorbital notch/foramen 31 mm (range 20 to 49 mm). The largest vertical distance from the supraorbital rim to its farthest exit point was 19 mm. Other than what is cited in literature, the variations concerning the configuration and the distance of the exit point(s) of the supraorbital nerve were so significant that all forehead operations, especially those using endoscopic techniques, must take into account these findings.

Adult↗

PubMed1998

Lateral ankle ligaments and tibiofibular syndesmosis. 13-MHz high-frequency sonography and MRI compared in 20 patients.

To test the ability of ultra-high frequency ultrasound (13 MHz scanner) to distinguish between intact and ruptured ligaments on the lateral side of the ankle, we examined 20 patients with an acute inversion injury with MRI and ultrasound. When judged by the MRI diagnosis, an injured anterior talofibular ligament was correctly diagnosed by ultrasound in 13 of 14 and an intact anterior talofibular ligament in 5 of 6 patients. In the case of the calcaneofibular ligament, 4 ruptured and 16 intact ligaments were diagnosed equally well with both methods. The injured anterior tibiofibular ligament was correctly diagnosed by ultrasound in 6 of 9 patients, while the intact ligament was correctly recognized in 10 of 11 patients. Our findings indicate that it is possible to distinguish injured from intact ligaments sonographically.

Fibula↗

PubMed1997

Thickness distribution of the subchondral mineralization zone of the trochlear notch and its correlation with the cartilage thickness: an expression of functional adaptation to mechanical stress acting on the humeroulnar joint?

BACKGROUND: The thickness of cortical bone and the density of cancellous bone have been shown to reflect local mechanical stress. However, little is known whether this also applies to the thickness of the subchondral mineralization zone (SMZ). Since the humeroulnar joint may be regarded as a model of bicentric load transmission, we examined the thickness distribution of the SMZ of the trochlear notch. METHODS: Fourteen trochlear notches were examined. Eight joint surfaces of these ulnae were completely divided, 4 incompletely subdivided, and 2 remained undivided. After embedding, sagittal sections were prepared. The thickness distributions of SMZ and cartilage were measured, graphically reconstructed, and the correlation between the two calculated for each joint. RESULTS: The thickness of the SMZ lies between 120 and 1,400 microns. Regular patterns were observed with ventral and dorsal maxima, with close correlations between the type of joint and the thickness distribution of the SMZ. The cartilage thickness varied between 350 and 2,000 microns. The pattern of cartilage thickness differed significantly from that of the SMZ. The mean correlation coefficient between SMZ and cartilage thickness was 0.3. CONCLUSIONS: The SMZ thickness depends upon the type of joint and appears to be an expression of the local loading history of the SMZ. The bicentric transmission of force at the humeroulnar joint is reflected in the bicentric distribution of SMZ thickness. A possible explanation for the different distributions of SMZ and cartilage could be the differing types of local mechanical stress acting on bone and cartilage, and/or the different reactions of osteocytes and chondrocytes.

Adaptation, Physiological↗

PubMed1997

Direct comparison of contact areas, contact stress and subchondral mineralization in human hip joint specimens.

X-ray densitometric and CT osteoabsorptiometric findings suggest that in the human hip subchondral mineralization patterns change from bicentric to monocentric as a function of age. It has been hypothesized that these changes indicate an alteration in the geometric configuration of the joint from incongruous to congruous, possibly associated with the onset of osteoarthrosis. The purpose of this study was therefore to directly compare contact rates, contact stress and subchondral mineralization in the hip joint. Twelve specimens without cartilage lesions (ages 34-86 years) were investigated. Simulating the mid-stance phase, the contact areas were determined by polyether casting and the contact stress with Fuji film. The distribution of subchondral mineralization was assessed non-invasively with CT osteoabsorptiometry. At small loads the load-bearing areas were located at the periphery of the lunate surface. In some joints they were found in the acetabular roof and expanded, with higher loads, to the center of the lunate surface and the anterior and posterior horns. In other joints, the contact areas were recorded at lower loads in the anterior and posterior horns, and only at higher forces they merged in the acetabular roof. The maximal contact stress ranged from 8 t 9 MPa at 300% body weight. Maxima of subchondral mineralization were recorded in the acetabular roof, in the anterior and posterior horns, or in all three locations. There was no clear correlation between the distribution of contact and pressure, and the pattern of subchondral bone density. Incongruity is shown to strongly affect the distribution of contact and pressure in the human hip joint. However, the pattern of subchondral mineralization cannot be readily explained in terms of the contact areas and contact stress during mid-stance. Incongruity may give rise to tensile stresses in the subchondral bone, and the construction of the pelvis as a whole may play an important role in subchondral bone loss loads and adaptation.

Adult↗

PubMed1997

Mechanical implications of humero-ulnar incongruity--finite element analysis and experiment.

Previous studies show that the humero-ulnar joint is physiologically incongruous [Eckstein et al. (1995a) Anat. Rec. 243, 318-326] and exhibits a bicentric (ventro-dorsal) distribution of subchondral mineralization [Eckstein et al. (1995b) J. Orthop. Res. 13, 286-278]. We therefore asked: (1) Does humero-ulnar incongruity bring about a bicentric distribution of contact pressure? (2) Do tensile stresses occur in the subchondral bone of the trochlear notch that are in the same order of magnitude as the compressive stresses? (3) Do ventral and dorsal maxima of subchondral bone density correlate with a bicentric distribution of strain energy density? To that end, a two-dimensional finite element model was designed. The shape and material properties of the bones were based on CT and the boundary conditions selected to agree with resisted elbow extension at 90 degrees of flexion. The incongruity and contact areas were determined experimentally from casts, and the pressure distribution with Fuji Prescale film. In the model and the experiment contact stresses above 2 MPa were recorded in the ventral and dorsal parts of the joint, and values below 0.5 MPa in the depth of the notch. In the model, tensile stresses of 2.9 MPa were observed in the subchondral bone of the ulna, but not in the humerus. The subchondral strain energy density yielded a bicentric pattern in a model with homogeneous subchondral bone properties. It is shown that humero-ulnar incongruity brings about a bicentric distribution of contact pressure, a tensile stress in the notch that is in the same order of magnitude as the compressive stress, and a distribution of strain energy density that correlates with subchondral density patterns.

Adult↗

PubMed1997

Non-invasive determination of cartilage thickness throughout joint surfaces using magnetic resonance imaging.

Data on articular cartilage thickness in the living are important for the design for computer models, aimed at preoperatively assessing the effect of surgical procedures on joint contact and load transmission, and for the calculation of cartilage material properties from its deformational behavior as determined during arthroscopy. A non-invasive method for measuring cartilage thickness in living subjects is, however, not available. A technique based on magnetic resonance imaging has therefore been tested for assessing articular cartilage thickness throughout joint surfaces. The accuracy is determined by comparing cartilage thickness maps obtained from three patellar specimens with a fat-suppressed three-dimensional gradient-echo sequence (resolution 2 x 0.31 x 0.31 mm) to those obtained with CT arthrography, A-mode ultrasound and anatomical sections. The distribution patterns are quantitatively compared using image analysis. The highest agreement was obtained for MRI and the sections (50% identical pixels), but all techniques yielded very similar results. On average, MR slightly underestimated the cartilage thickness compared with CT and the sections, and overestimated it compared with ultrasound. No evidence of differences in the degree of similarity could be detected in areas of thin and thick cartilage. We conclude that, if the resolution and accuracy of the method presented are considered acceptable, MRI is available for repeatable determination of topographical maps of articular cartilage thickness in living subjects. These data can be used to determine joint contact and stress in computer models and to calculate cartilage material properties in vivo.

Adult↗

PubMed1997

[Three-dimensional thickness and volume measurements of the knee joint cartilage using MRI: validation in an anatomical specimen by CT arthrography].

PURPOSE: In the present study we intended to validate knee joint cartilage volume and thickness measurements with MRI. METHODS: Ten fresh cadaver knees (age 29 to 64 yrs.) were sagittally imaged, using a fat-suppressed FLASH-3D sequence with a resolution of 2 x 0.31 x 0.31 mm3. Then, a contrast agent was injected and the specimens submitted to CT arthrography. From both modalities the patellar, femoral, and tibial cartilages were segmented semiautomatically and reconstructed three-dimensionally. The cartilage thickness was determined independently of the sectional plane, based on a "minimal distance algorithm". RESULTS: The volumes and the regional distribution patterns yielded a very high degree of similarity on direct comparison of both imaging modalities. The average volume error between MRI and CT was 3.8% (+/- 3.0%), the correlation 0.998, the slope of the regression line 1.04 and the gamma-intercept -80 mm3. The analysis yielded no significant differences between the two methods (Wilcoxon signed rank test, 5% level) in the patella, femur, medial, and lateral tibia. CONCLUSION: The results suggest that, based on a fat-suppressed FLASH sequence with high resolution and three-dimensional concepts of digital image analysis, the cartilage volume and thickness can be analysed non-invasively and with high accuracy by MRI.

Algorithms↗